Evaluation of Groundwater Vulnerability to Pollution using GIS Based DRASTIC Method in Koradi, India - A Case Study

Groundwater (GW) contamination due to urbanization, industrialization and agriculture is a major environmental problem in India. The present case study aims to estimate the vulnerability of the aquifer with the help of GIS based DRASTIC method. A micro watershed, characterized by Granites and Gondwana Formation in the vicinity of Koradi, 15 km from Nagpur in Central India has been considered. The DRASTIC method accounts for hydrogeological parameters like depth to water, net recharge, aquifer media, soil media, impact of vadose zone and hydraulic conductivity. The DRASTIC index (DI) for GW vulnerability to pollution is calculated as the sum of the product of ratings and weights assigned to each of the parameter on the scale of 1 to 10 and 1 to 5 respectively. A Groundwater vulnerability map has been prepared using the Arc GIS software (Version 10.1) and it delineates the total study area into two vulnerable zones with vulnerability score ranging from 107 to 142 and indicates that 33% and 67% of the area lies in low and moderate vulnerability zones respectively. The vulnerability score as obtained is also verified with field data.